Fuse



April 5, 1938. D. E. CARNEY 2,113,169

FUSE

Filed May 25, 1929 INVENTOR Patented Apr. 5, 1938 UNITED STATES PATENT OFFICE FUSE Application May 25, 1929, Serial No. 365,929

3 Claims.

My invention relates to certain new and useful improvements in fuses, more particularly of the knife blade type of fuses commonly employed for protecting electrical circuits from currents which'are above their safe carrying capacity.

The electrical industry has long recognized the need and desirability of an efficient fuse of this type, which is refillable, simple in structure, and not open to liability of explosion upon the occurrence of a blow out; Such refillable fuses as have been heretofore developed, contain inherent defects due to multiplicity of holding and sealing washers, necessarily assembled as separate units and thus multiplying the possibilities for presence of dirt and grease in the assembled fuse;

the cause of explosions.

The present invention has been designed to overcome and avoid all defects of prior art practice and has as an essential object the provision of a refillable fuse assembled as a two part structure.

Another object is the provision in a fuse of this character of means permanently associated, as by coupling? with an end cap or retaining member, for releasably locking and maintaining the fuse strip assembly against movement relative to the fuse casing.

A further object is the provision in such a fuse, of a detachable end closure and sealing means having self contained blade terminal locking means shiftably associated therewith.

Additional objects of the invention are to pro- ,vide a fuse of the character described which will greatly facilitate and expedite the renewal of the fuse links embodied therein, which includes a pair of non-bridged terminal blades, which is simple in its construction and arrangement, du-

rable and eflicient in its use, positive in its action,

and comparatively inexpensive to manufacture, assemble, repair and maintain.

With the foregoing and other objects in view which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it

being understood that changes in the precise embodiment of the invention hereinafter disclosed can be made within the scope of what is claimed 50 without departing from the spirit of the invent on:

In the drawing wherein like numerals of reference designate corresponding parts throughout the several views:

Figure l is a longitudinal cross sectional view of a knife blade type of fuse constructed in accordance with the invention.

Figure 2 is a bottom end view thereof.

Figure 3 is a side view of my improved fuse.

Figure 4 is an end view of the fuse casing. 5

Figure 5 is a top plan view of the device.

Figure 6 is a top plan view of the locking ring, and Figure 7 is a bottom plan view ofthe lock washer associated with the latter.

Figure 8 is a side view of the terminal blades joined by the interposed fuse links, with certain of the elements shown in Figure 1 as associated with the blade 1 being omitted.

Referring in detail to the drawing the fuse casing A comprises a hollow cylinder l which is open at both ends thereof, and constructed from any suitable insulating-material. The top and connecting sleeves, respectively indicated at 2 and 3, which are fixed to the respective ends of the cylinder I in any suitable manner.

The connecting sleeves 2 and 3 are provided with exteriorly threaded outer end portions for the engagement of the interiorly threaded clamping caps, respectively indicated at l and 5. The outer end of each of the latter is formed with an inwardly disposed annular flange 6'. The outer peripheries of the clamping caps 4 and 5 are knurled to facilitate their manipulation when effecting their engagement with respectiveconnecting sleeves 2 and 3, and their removal from the latter.

A pair of aligned terminal blades, respectively indicated at 6 and l, are mounted to project from respective ends of the fuse casing A,,and are formed with reduced inner end portions 8. A plurality of suitably spaced fuse links 9 are detachably connected to respective end portions 8 within the fuse casing, by means of bolts It. The fuse links 9 are constructed from some easily fusible metal and of such size'that an unsafe, electrical current melts them and breaks the circuit, in the manner well known in the art.

The fuse links 9 are sufllciently rigid to support the terminal blades 6 and I in fixed longitudinal alignment relatively to each other, and in consequence, no bridge member, other than the fuse links 9, is required for connecting and supporting the terminal blades 6 and I.

v A cap washer II, a spacing washer l2 and a lock washer l3, are positioned flatly against each other and are fixedly and permanently connected to the terminal blade I, in any suitable manner, at the juncture of the latter with its associated reduced portion 8.

The diameter of the spacing washer I2 is somewhat'less than the diameters of the cap washer II and of the lock washer I3, whereby the combination of the three washers II, I2 and I3 virtually establishes a. peripheral, circumferentially extending groove I4, for the reception of the annular flange 8', of the clamping cap 5.

The outer end of each of the connecting sleeves 2 and 3 is provided with a pair of diametrically opposed flanges I5, which are formed with a pair of diametrically opposedrecesses IS. The lock washer I3 carries a pair of fixed, inwardly disposed, and diametrically opposed lugs II, which extend into and engage in the recesses I6 to prevent the rotation of the associated washers II, I2 and I3 and of the terminal blade I fixed to the latter.

The engagement of the flange 8 in the groove I4 permits of the free rotation of the clamping cap 5 in effecting the attachment of the' latter ment for the bottom end of the fuse casing A,

and further serve to rigidly support the terminal blade I in the latter.

. The top of the fuse casing is closed by a lock washer I8 andan associated locking ring I8. The locking ring I8 is positioned on top of the lock washer I8 and is shiftably connected to the latter by a pair of headed guide pins I9. The guide pins I9 are fixed in the apertures 2| to the lock washer I8 and extend outwardly through a pair of guide slots 20, which are formed in the locking ring I8.

A pair of diametrically opposed, headed, connecting pins 22 are fixed in apertures 23 to-the locking ring I8. The heads of the connecting pins 22 overlap the outer side of the inner peripheral edge margin of the flange 6', of the clamping cap 4. The engagement of the connectingpins 22 with the flange 6' is such as to permit of the free rotation of thecap 4 on the locking ring I8, while connecting the cap 4 to the latter. The connecting pins 22 further serve as hand-holds for facilitating the adjustment of the ring I8 with respect to the lock washer I8.

- The lock washer I8 is formed with an oblong r bar 25 which is fixed to the latter at its juncture with the associated reduced portion 8. The purpose of the flash bar 25 is to prevent the potential passage of any flash back through the slot 24 in the event of a blowout of the fuse.

The lock washer I8 is provided with a pair of diametrically opposed, inwardly extending lugs 28, which engage in the recesses I8 formed in the flange I5 of the connecting sleeve 2, for

preventing the rotation of the lock washerl8 in the latter. The lock washers I8 and I3 are identical in constructionand arrangement except that the former is provided with the fixed guide pins I9 and is not fixed to its associated terminal blade 8. n

The locking ring I8 is formed with a pair of diametrically opposed slots 21 which are open at the inner periphery of the former. The ring slots 21 are provided to allow the passage of the terminal-blade 8 through the locking ring I8. The side edge margins of the terminal blade 8 are also provided with a pair of aligned slots 28, which are oppositely disposed to each other and open at their outer ends. The blade slots 28 are adapted for the reception of the inner peripheral edge margin of the locking ring I8 for rigidly locking the terminal blade 6 to the lockwasher I8, as clearly shown in Figure 5.

The peripheral edge margin of the lock washer I8 overlaps the outer end edge of the connecting, sleeve 2, and when the cap 4 is secured to the connecting sleeve 2, the lock washer I8 and lock ring I8 are securely clamped between the flange 8 of the cap 4 and the outer end edge of the connecting sleeve 2.

In practice, my improved fuse is taken entirely apart as follows:

The clamping cap 4 is first partially released on the connecting sleeve 2. The locking ring I8 is then shifted on the lock washer I8, a distance permitted by the guide pins III in the guide slots 28, which will release the ring from the blade slots 28 and bring the ring slots 21 into proper registration with the blade 8 to allow the latter to be drawn inwardly through the locking ring I8. The clamping cap-'4 is now entirely unscrewed from the sleeve 2, thereby allowing the cap 4, the locking ring I8 and the lock washer I8 to be entirely removed from the blade 8 and from the fuse casing A. The other cap 5 is now unscrewed from the sleeve 3, permitting of the said cap 5, together with the attached washers I I, I2 and I3 and the terminal blades 8 and I to be entirely removed from the fuse casing A.

It will here be noted that the lock washer I8 is connected to the locking ring I8 by the guide pins I9, and that the locking ring I8 is in turn connected to the clamping cap 4 by the pins 22. These parts constitute theclosure element for the top of the fuse casing and are, of course, removed from and replaced to the latter as a unit.

As the clamping cap 5 is shiftably connected to the washers II, I2 and I3 and the latter in turn to the terminal'blades 8 and I and the fuse links 9, all of these parts are also removable from and replaceable to the fuse casing A, as a unit.

By this construction and arrangement the top and bottom closure elements for the fuse casing A, may be removed from or replaced to the latter in only two separate .mits, thereby facilitating and expediting the replacement of the fuse links 9 when required. I

In service the fuse is a two-part unit which does not require an entire disassembly in. replacing blown fuse elements. Under service conditions a replacement is effected simply by partially releasing the cap 4 and bringing the ring slots 21 into registration with the blade 8 whereupon the 'cap 5 is unscrewed to remove its assembly from the bottom of the fuse casing. The blade 6 is then allowed to drop inwardly within the fuse casing and by partially rotating the same it may be removed through the lower end of the casing.

A new fuse strip structure is then connected between the terminal blade extensions 8 and the entire assembly is reinserted within the casing from right to left as seen in Figure 1 moving the blade 8 through the end cap assembly 4. With the cap 5 screwed home the fuse strip assembly is properly positioned and the cap 4 is then given an advance turn to bringthe lock ring I8 into interlocking engagement with" the blade 6. It will be noted that under the conditions just described the cap 4 constitutes and remains a part of the casing I so that the fuse is in reality a two-part fuse.

The present invention provides a most eflicient device of its kind. which may be cheaply manufactured and conveniently maintained.

What I claim is:

1. In a fuse, a casing, a fuse strip assembly inse'rtable though the casing and having projecting terminals-a closure for one end thereof, and

a unitary locking and closure cap connected to the other end of the casing in assembled or disassembled positions and engageable with the proiecting terminal of the strip assembly to prevent axial and rotary movement thereof.

2. A two-part renewable fuse including a casing having a combined unitary locking and closure cap on its outer end connected therewith in assembled or disassembled positions, and a fuse strip assembly with projecting terminals insertable through said casing carrying a permanently attached casing closure cap on the inner'end portion of the same, the outer projecting terminal of the strip assembly being engageable by the combined locking and closure cap to prevent axial and rotary movement thereof when assembled.

3. A two-part refillable fuse; one part comprising a fuse strip assembly having as a permanent part thereof means for closing a casing end; and

the other part comprising a casing having a unitary end closure and fuse strip locking cap on one 

